Rifling-tool and method of using same



C. G. ALLGRUNN.

RlFLlNG TOOL AND METHOD OF USING SAME.

APPLICATION FILED FEB. 23. 1918.

Patented July 22, 1919.

CARL G. ALLGRUNN, OF ROCHESTER, NEW YORK.

RIFLING-TOOL AND METHOD OF USING SAME.

Specification of Letters Patent.

Patented July 22, 1919.

Application filed February 23, 1918. Serial No. 218,722.

To all whom, it may concern Be it known that I, CARL G. ALLGRUNN, a citizen of the United States, residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Rifling- Tools and Methods of Using Same, of which the followingis a specification.

This invention relates to tools for cutting the rifling grooves in gun barrels and its object is to provide a new and improved tool and a new method of using it by means of which the operation of rifling a gun barrel is simplified and the time for performing this operation is greatly reduced.

With this and other objects in view, this invention presents a novel construction comprising a combination and arrangement of parts which will be fully illustrated in the drawings described in the specification and pointed out in the claims at the end thereof.

In the corresponding drawing- Figured is a diagrammatic view of a rifling machine.

Fig. 2 is a detail view of the improved rifling tool and parts associated therewith, the tool being shown partly in section.

Fig. 3 is a vertical section through the pilot for the tool holder, the section being taken on the line 3"'-3" of Fig. 2.

Fig. 4 is a vertical section through the tool holder on the line 4* X of Fig. 2, showing an elevation. of the oil-distributing sleeve of the tool.

Fig. 5 is a vertical section through the tool-holder onthe line 4"4" of Fig. 2 looking toward the. right hand end of the toolholder and showing a front elevation of the tool mounted thereon.

Fig. 6 is a vertical cross-section through the tool-holder and guide-sleeve therefor the section being taken on the line of (i -43" of Fig. 2.

Fig. 7 is a cross-section through the shank of the tool-holder the section being taken on the line-of 7*- X of Fig. 2.-

Fig. 8 is a detail perspective view of the rifling tool proper;

Fig. 9 shows cross sections through three different broaches of one series.

In the several figures of the drawing like reference numerals indicate like parts.

Gun barrels are rifled for the purpose of giving greater accuracy of fire. This rifling consists of a string of parallel grooves, running spirally along the inside of the barrel.

The cutting of these rifling grooves is the subject of my invention. The rifiing operation has heretofore been done by means of a tool which is provided with two cutting edges that are placed diametrically opposite each other on the rim of the tool holder, each of which cutting edges cuts a single groove so that two of the spiral grooves are cut at a time by the machine. If the gun barrel contains 21 rifiing grooves, 12 operations are necessary to make one cut in each of the 24 grooves. Each groove requires a number of cuts in order to make it the desired depth. In a 3 gun about 24 cuts are necessary in each groove to bring it to the desired depth so that in all 12 tunes 24, or 288, cuts are necessary to complete the rifling operation of a 3 gun barrel having 21 grooves therein.

In some cases three or even four cutting edges have been used at a time, but in any case the total number of cutting edges used sin'lultaneously has never been more than a small fraction of the total number of grooves to be cut in the barrel.

lVith larger guns the'number of grooves out are greater in number.

The location of the cutting tools for the different rifiing grooves is changed by rotating the groove of the rifling bar for each change of grooves operated on, the cutting tools remaining stationargtv in the cutting head.

It has been customary for the cutting tool to take off a thin out of one or two thousandths of an inch, and after each out has been completed, it has been customary to advance the cutting edge radially so as to use the same cuttmg edge for successive cuts of increasing depth. It has been necessary after each cut is made, to draw the cutting edges in radially so that they will not come into contact with the gun barrel on the return movement of the tool holder. Failure to move the cutting edges in has caused the scoring and consequent loss of many gun barrels. Therifiing operation is one of the last operations to be performed in the making of the gun barrel andthe loss is, therefore, very great if the gun barrel is spoiled thereby because it means the loss of all the work previously done on the gun.

In rifling 3" or 7 5 mm. gun barrels by my invention but twelve cutting operations are necessary to complete the work. All of the rifling grooves are cut simultaneously and uniformly.

In the method used for rifling the same gun-barrel by means of the tool comprising this invention only 12 cutting operations are necessary to produce the same result. For this purpose a special cutter 1 is provided which is mounted on the toolholder 2 as will hereinafter be described. This cutter has one cutting ed e thereon for each roove to be cut in the arrel.

The ri ing of a gun-barrel is done on a machine which is provided with suitable means on which a gun-barrel 3 is centered and rigidly held in place thereon. The gunbarrel 3 when placed on this machine has its bore completely finished and the mouth of the gun-barrel is held in place on the rifling machine ready to allow the rifling tool to enter the barrel.

. The rifling tool is mounted on the end of the rifling bar 4 which passes through the head-stock 5 of the machine.- The rear end of the rifling bar 4 is mounted in a movable tail-stock 6 which is provided with athreaded sleeve 7 that engages the lead-screw 8 suitably mounted in the machine.

On-the rotation of the lead-screw in one direction the tail-stock which carries the end of the rifling bar is moved toward the left and. forces the rifling tool mounted on the front end of the rifling bar into the bore of the gun-barrel.

In order to give the rifling tool the required rotation while passing through the a bore of the gun-barrel so as to produce the spiral grooves which form the rifiing of the gun-barrel, the rifling bar is provided with a longitudinal spiral groove 9 in which engages a stationary pin 10 provided in the head-stock 5.

On the movement of the rifling-bar forward to the leftor rearward to the right in Fig. 1 thepin 10 operates to give the rifling bar a twisting motion corresponding to the lead of the spiral groove 9 provided therein. It is this twisting motion'of the rifling bar which forces the rifling tool along in a spiral motion through the bore of the gun-barrel. The rifling tool mounted on the end of the rifling-bar 4 comprises the tool-holder 2 which is provided with the shank 11 on one end of the tool-holder and the extension 12' which is of reduced diameter on the other end thereof. A pilot 13 and the oil-distributlng sleeve 14 is slipped over the extension 12 and is firmly forcedagainst the rlfiing tool 1 by means of the clamping nut 15 screwed to the end of the threaded extension 12.

The rifling tool 1 is held in place and is properly centered on the tool holder tubehy means of the keys 16 and 17 which proect 1nto corresponding key-ways provided in the tool 1. The rear of the tool '1 rests against the shoulder 18 providedin the toolholder 2 against which it is firmly held by means of the clamping-nut 15 which forces both the pilot I?) and the oil-distributing sleeeve 14 against the front face thereof.

The central portion of the tool-holder 2 is surrounded by the guide-sleeve 19 which corresponds in diameterto the bore of the gun-barrel whichis to be rifled with the rifling tool 1. The guide sleeve'19 extends from the rear of the rifling tool 1 to a shoulder 20 provided around the periphery of the tool-holder "2and near the left-hand thereof. The guide-sleeve 19 is also clampedin place on the tool-holder by means of the clamping nut 15 because the pressure appliedto the tool 1 is communicated to the left-hand end of the sleeve 19 which forces the right-hand end thereof firmly against the shoulder 20 of the tool-holder.

The shank 1.1 of the tool-holder is ta- I pered so as to fit into a corresponding socket provided in the end of the rifling bar 4 in which it is held in place by means of a key which passes through the rifiing bar and the slot 21 provided in the shank 11 of the toolholder.

For the purpose of supplying oil or other liquid to the rifling cutter l for the proper lubrication thereof the tool-holder is provided with a pair of longitudinal channels,

22 and 23 which pass through the shank 11 on either side of the slot 21 and terminate into the cross-slot 24. A central but larger longitudinal channel 25 in turn branches off radial openings 26 in the tool-holder to the radial grooves 27 on the end of the sleeve 14, so as to supply the cutting edges of the rifling-tool with the necessary lubricant.

The pilot 13 mounted near the front extension 12 of the tool-holder is provided with three gulding shoes 28, 29 and 30 which are suitably spaced apart on the periphery thereof leaving open spaces between them. The outslde diameter of the pilot except the front end thereof corresponds to the inside diameter of the gun-barrel which is to be rifled and serves to guide the tool through the gun-barrel and properly centers it therein before 1t enters the mouth of the gun-barrel. The front end of the pilot 13 is slightly tapered so as to allow the pilot to enter the bore of the gun-barrel with ease and center it therein.

The rifling tool 1 which performs the cutting operation comprises the circular disk 31 which has the broaching teeth 32, 32 provided on the periphery thereof. These broaching teeth are slightly under-cut at the front end thereof by means of the circular groove 33 which is provided in the front face of the tool adjoining the cutting edges of the broaching teeth.

'The broaching teeth 32 taper toward the rear and slightly decrease in height so that the front endthereof forms a very sharp cutting edge, the outline of which conformsto the grooves to be cut into the bore of the gun-barrel.

The spaces provided between the broaching teeth 32 are deep enough so that the lands of the bore of the gun-barrel will not be cut thereby at these points.

The ridges or lands for the rifiing are thus left in the barrel as the cutting tool passes through the bore of the barrel and forms the grooves between the lands.

These spiral grooves between the lands are cut by a series oftools preferably twelve in number each of which is slightly larger than the other. The broaching teeth in the first of these cutters are flat at the top and are v not very high and the outline of them is shown in elevation in Fig. 5. Each succeeding cutter has its teeth slightly increased in height until the last or finishing cutter is provided with teeth which have a cutting edge corresponding to the outline and depth of the rooves which are to be cut into the finished bore of the barrel. These cutters are used in succession the smaller cutter being rep-laced by the next larger cutter for the next operation, each cutter cutting about two thousandths of an inch radially from the grooves. Each cutter goes forward through the barrel once and is taken off at the end of the forward stroke after which the tool holder returns blank for the next cutter.

The open spaces in the pilot left between the segmental guiding shoes are provided for the purpose of allowing the chips from the cutting tool to pass out through them as fast as the chips are out off so as to leave the hold all the chips that may accumulate in a single cut. This space is cleaned out at the end of each cutting operation before the rifling bar is drawn back through the barrel of the gun. The short chips are readily flushed out with the oil while the long chips or ribbons accumulate to a greater or less extent in the open space between the pilot and the tool.

As each cutting tool wears, it can be ground down to the next smaller size and used over again. In this way a single large cutter would pass through all the sizes of the series and eventually become the smallest cutter and only the largest size cutter need be furnished new as each reduction in the sizes of the cutters takes place.

In operation, the barrel of the gun is first placed in the machine and properly centered therein, and the rifiing bar is equipped with the shank, cutter, sleeves and pilot and made ready for use, the parts being held in place by the nut. The rifiing bar with the small cutter is driven through the barrel of the gun until the cutter emerges from the far end of the gun. The chips are then wiped off and the nut, pilot and oil distributing sleeve taken off of the shank and the cutter is then removed and the oil distributing sleeve and pilot and nut are replaced on the shank, after which the rifiing bar is drawn back through the barrel of the gun. Then the oil distributing sleeve and pilot are again taken off and the next larger cutter is put on the shank, after which the rifling bar is again driven through the barrel. This operation is repeated with each successive larger cutter until all twelve cutters have been used in succession, using one at a time. In a 3" gun, each operation requires between 2 and 3 minutes, and with the passage of the last and largest cutter the rifling of the gun is comhas passed into the powder chamber, the oil is turned off and remains turned off until the cutting operation of the next cutter begins.

From the foregoing it will be seen that the rifiin operation on a gun-barrel by means of this tool is completed in twelve operations each of which consists of forcing one of the special cutting tools through the inside ofthe barrel by means of the rifling bar.

I claim:

1. The process of rifling a gun-'barrelwhich consists in forcing one at a time a series of circular disks having broaching teeth integral therewith and equally distributed over the periphery thereof through said gun-barrel, the teeth on said disks being higher in each succeeding disk that is forced through the gunbarrel.

2. A rifling tool comprising a disk, said disk having broaching teeth integral therewith and distributed over the periphery thereof, each of said teeth having a sharp cutting edge at the front thereof and having its body inclined laterally toward the rear thereof to accommodate the different pitches of the spiral grooves cut by said teeth.

3. In a rifling tool, the combination of the tool holder, said tool holder having a pilot mounted at the front thereof, a tool comprising a disk having broaching teeth integral therewith and equally distributed over the periphery thereof mounted on said tool holder in back of said pilot, a detachable guiding sleeve mounted on said tool holder in back of said tool and means for attaching said tool holder to the end of a rifling bar.

4. The process of rifling a gun-barrel which consists in forcing one at a time a series of elements having broaching teeth integral therewith completely through said gunebarrel, the teeth on said elements being higher in each succeeding element that is forced through the gun-barrel.

5. A rifling tool comprising a circular disk, said disk having cutting teeth integral therewith and equally distributed around the periphery thereof, each of said cutting teeth having a sharp cutting edge at the front thereof and having its body inclined on one side to accommodate the different pitches of the spiral grooves cut by said teeth.

6. A rifiing tool comprising a circular disk, said disk having cutting teeth integral therewith and equally distributed around the periphery thereof, each of said cutting teeth having a sharp .cutting edge at the front thereof and having its body inclined on one side to accommodate the different pitches of the spiral grooves out by said teeth, said tool being under cut on its forward face.

7. A rifiing tool comprising a circular disk having cutting teeth integral therewith and equally distributed around the periphery thereof, each of said cutting teeth having a sharp cutting edge at the front thereof and having. its body extending parallel to the axis of the tool on one side and inclined on the other side to accommodate the different pitches of the spiral grooves cut by said teeth.

8. A rifiing tool comprising a circular disk having cutting teeth integral therewith and equally distributed around the periphery thereof, each of said cutting teeth having a sharp cutting edge at the front thereof and having its body extending parallel to the axis of the tool on one side and inclined on the other side to accommodate the different pitches of the spiral grooves cut by said teeth each of said teeth sloping downwardly toward the rear thereof.

9. In a rifling tool, the combination of a shank having a shoulder thereon, said shank having an oil passage way extending therethrough, a sleeve at the forward end of said shank, a circular cutting disk interposed between said sleeve and said shank, said cutting disk having a plurality of cutting teeth thereon, said sleeve having an annular channel therein connecting with the oil passage way, slots on the periphery of said sleeve extending outwardly across the end thereof, through each of which slots a jet of oil is projected outwardly along the teeth and against the chips out thereby.

10. In a rifling tool, the combination of a shank, a shoulder on the forward end thereof, a stem extending forward centrally from said shoulder, a cutting disk carried on said stem, a sleeve on said stem resting against said cutting disk, a pilot on said stem having segmental shoes thereon, means for clamping said disk, sleeve and pilot on said stem.

11. In a rifling tool, the combination of a shank, a shoulder on the forward end thereof, a stem extending forward centrally from said shoulder, a cutting disk carried on said stem and resting against said shoulder, a sleeve on said stem resting against said disk and means for clamping said sleeve and disk against the said shoulder.

12. In a rifiing tool, the combination of a tool holder having a body, a shoulder on the forward end thereof, a stem extending forward centrally from said shoulder, a cutting disk carried on said stem and resting against said shoulder, a sleeve on said stem resting against said disk and means for clamping said sleeve and disk against said shoulder, said sleeve having an annular groove in the end thereof opening against the disk and a series of radial grooves on the end thereof.

13. A rifling tool comprising a circular cutting disk, said disk having cutting teeth integral therewith and distributed equally and continuously around the periphery thereof, one for each groove to be cut, a pilot mounted in advance of said disk with an open space between said pilot andthe disk adapted to receive the chips from said cutter, said pilot having radial open spaces therein through which the oil and chips can pass.

14. In a rifiing tool, the combination of a shank having a large shoulder thereon, a stem extending forward centrally from said large shoulder and having a small shoulder on the end thereof, a cutting disk carried on said stem and resting against said shoulder, a sleeve on said stem interposed between-said disk and'said large shoulder, a sleeve on said stem beyond the disk and means for clamping said sleeves and disk on said stem.

15. A rifling tool comprising a cutting disk, a pilot on one side of said disk and a detachable guide on the other side of said disk, and means for holding the pilot, disk and guide together and in correct alinement.

16. A rifiing tool comprising a cutting disk, a pilot on One side of said disk and a detachable guide on the other side of said disk and means for holding the pilot, disk and guide together and in correct alinement,

said means permitting the removal of the cutting disk.

17. A rifling tool comprising a cutting disk, a pilot on one side of said disk, a guide on the other side of said disk, and

v means for holding the pilot, disk and guide together and in correct alinement, said pilot being spaced apart from the disk with an open space between them. 7

18. A rifling toolcomprising a cutting disk, a vpilot on one side of said disk, a guide on the other side of said disk, and means for holding the pilot, disk and guide together and incorrect alinement, said pilot having openings extending longitudinally therein to permit the flush of chips and oil therethrough.

In testimony whereof I aflix my signature in the presence of two witnesses.

CARL G. ALLGRUNN. 

